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THE AM BULLETIN BOARD => Technical Forum => Topic started by: ve6pg on January 14, 2005, 08:52:06 PM



Title: viking2/122 vfo problem
Post by: ve6pg on January 14, 2005, 08:52:06 PM
HI FROM TIM..VE6PG/3...MY 122 VFO HAS A NOTICABLE CARRIER ON THE "PHONE" POSITION OF MY VIKING2. WHEN I PUT THE VIKING IN THE CW MODE ,I HAVE A NICE ZERO BEAT SIG ON MY NC300. WHEN I TURN TO THE PHONE POSITION, I CAN STILL HEAR THE CARRIER. IF I CHANGE THE BAND SWITCH ON THE VFO TO ANOTHER BAND,AND THEN BACK TO WHERE I WANT TO OPERATE,THE CARRIER IS GONE...BUT! WHEN I AM FINISHED TRANSMITTING(IS PHONE POSITION),THE CARRIER IS BACK,AND I HAVE TO CHANGE BANDS AGAIN ON THE VFO,AND BACK TO WHERE I WANT TO BE,AND THE CARRIER IS GONE...WHAT IS THE DEAL HERE!!!! ANYONE HAVE ANY IDEAS...PLEASE LET ME KNOW..
   73...TIM...ve6pg@rac.ca


Title: viking2/122 vfo problem
Post by: W1DAN on January 15, 2005, 08:13:11 AM
Hi Tim:

I noticed this with my Viking 2. The VFO signal was not that strong to interfere with my reception though. Possible shielding grounding improvements?

One far fetched idea would be to add a relay and/or switch to add some capacity to the tuning cap of the VFO to pull the frequency away from your receive frequency when in receive.

The VFO could probably be killed when in receive, but that would probably reduce stability.

Good luck,
Dan
W1DAN


Title: viking2/122 vfo problem
Post by: WA1GFZ on January 15, 2005, 04:32:21 PM
My 122 does the same thing and it doesn't hurt a bit after 25 years.


Title: viking2/122 vfo problem
Post by: WD8BIL on January 17, 2005, 03:01:21 PM
IIRC the 122 is grid blocked keyed !

Check for a leaky bypass or shaping capacitor either in the VFO or the keying line from the transmitter.

I don't have the schematic in front of me but I have 2 Viking/122 setups and hear no VFO signal in the phone mode on either setup.
After an AM transmission I have no signal present.


Title: Was Talking to Budley Tonight and...
Post by: WA1HZK on January 17, 2005, 10:34:03 PM
That VFO is Cathode Keyed. Look at the .005 cap across the key jack. It's probably leaky. There should be no current flowing in that tube when it's un-keyed. Thats our thinking as of tonights conversation.
Keith
WA1HZK


Title: viking2/122 vfo problem
Post by: wavebourn on January 17, 2005, 10:35:36 PM
What if to connect some high ohm resistor from cathode to some positive source?


Title: viking2/122 vfo problem
Post by: WD8BIL on January 18, 2005, 07:33:57 AM
That wud be a good mod Tolly. Drive that tube way into cutoff.
But if all is working as it should it really isn't necessary.

Another thought is the plate or mode switch on the Viking may be defective. One side of the plate switch turns on the B+ the other side keys the VFO in phone.

Regardless .... something isn't working right.
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